The proposed research is aimed at studying the steps which lead to the conversion of mesenchyme cell into a cartilage cell and the mechanisms by which cartilage cells control the synthesis of extracellular matrix components. The approach involves the use of tissue culture systems derived from limb and cartilage cells, which will be manipulated with several environmental factors, including cartilage conditioned medium. These factors will be used as tools to elucidate regulatory steps in the production of components of cartilage matrix.